Since the coupling windings of conventional clutch and brake device are installed on the outer side of clutch disc and brake disc respectively, the directions of the magnetic forces generated by the coupling windings and the brake windings are the same as that of the movement of the clutch disc or the brake disc. Meantime because of small magnetically effective area, the effective pulling torque is small and thus the accuracy of transmission and braking is reduced. Furthermore, because the coupling windings and brake windings are installed on the outer side, the construction is complicated and the fabrication and the assembling are difficult.
Another type of conventional device is known as such that the coupling winding is installed in the clutch member and rotates therewith. It is also known as a prior art that the brake winding is installed in the brake member. However, since the coupling winding rotates with the clutch member, the wiring thereof is very difficult and requires brushes which are subject to break down. Moreover, since the device having the brake winding installed in the brake member has only one set of winding, its magnetically effective area is small and the pulling torque is not sufficient to give effectiveness to the accuracy of braking.
The main object of this invention is to improve the aforesaid drawbacks of conventional clutch and brake devices and to provide a novel device in which the transmission and the braking with larger torque are obtained with the magnetic flux passing through the whole clutch disc or brake disc to increase the effective area for magnetic effect whereby the pulling torque is increased and thus the transmission torque and the braking torque are increased consequently.
Another object of this invention is to provide such a clutch and brake device that the winding is split in two sets of winding which are connected in the opposite directions to minimize the inductance and the reactive electromotive force accordingly. The response is quick and the operation is accurate, therefore the transmission function of the clutch is fast and the braking function of the brake is accurate.
Still another object of this invention is to provide a clutch and brake device of simple construction that will not break down and also is easy to fabricate and to assemble.
Since the coupling winding of this invention fixed onto the supporting means extends within the flywheel-and-clutch member and is segregated from the flywheel-and-clutch member by a non magnetically inductive material, therefore, the magnetic flux passes through the whole clutch disc with which the effective area of magnetic effect is increased and the pulling torque is increased accordingly. The construction of this invention is simplified, not subject to break down, and easy to fabricate and to assemble.